Lubricants containing nitrogenous thiomolybdates



u fed t es P t LUBRICANTS CONTAINING NITROGENOUS THIOMOLYBDATES I NoDrawing. n1... May 7,'1956,Ser.No.582,924

I '9 Claims. (Cl. 252-46.4)

The present application is acontinuation-in-part of application Serial No. 480,611, filed January 7, 1955, now US. Patent No. 2,909,541.

The present invention relates to lubricants containing nitrogenous 'thiomolybdates and the use thereof in the lubrication of metals. 3 v

A primary object of the present invention is the embodiment of lubricants containing in solution a sulfur compound of molybdenum which is decomposable, under the influence of the heat liberated by friction between parts in contact, to provide a deposit whichfills the irregularities of the said surfaces and protects themagainst wear, con- 'siderably reducing their 'coefl'icient of friction. The thiomolybdates of organic bases fulfill these requirements.

The only thiomolybdates of organic bases heretofore prepared have been the thiomolybdates of piperazine and piperidine. These products were prepared ,by Debut,

duct and Velluz (Bulletin de la Ste Chin'iique de France, 1932,51, 1571) by dissolving molybdic acid in an aqueous solution of the base, and then passing a stream of hydrogen sulfide into such solution for 12 to 24 hours. The thiomolybdate was obtained in: the form of brick red crystals, by filtering the solution.

The aforesaid copending application 7 discloses and claims the new nitrogen-containing-thiomolybdates.used according to this invention, as well as the preparation of such thiomolybdates. The process ofpreparation accordingto thesaid application is not only more rapid and more economical than the aforesaid'prior process, but 'it also makes it possible to prepare the' thiomolybdate of any nitrogen-base whatever, thus giving rise to an entire new series of compounds, which are of considerable interest wherever it is desired to produce an insoluble sulfur compound of molybdenum by the thermal decomposition of a'solution of a thiomolybdate, and especially in the lubricants field.

The preparation of the thiomolybdates of nitrogen bases is achieved, according to the said copending application, either by admixing aqueous solutions of sodium thiomolybdates and hydrochlorides, sulfates, hydrobromides or other soluble salts of organic bases, or by incorporating the salt of the organic base in the solid state in the thiomolybdate solution in very slight excess over the theoretical quantity. The reaction takes place very rapidly. The thiomolybdates appear in the form of crystals, generally of brick-red color, with the color varying somewhat with the nature of the base. The yields are practically quantitative.

The use for lubrication purposes of the thiomolybdates of piperazine and pipe'ridine, the only prior known compounds of this class, has never before been envisaged. The present invention is directed particularly to the utilization of all thiomolybdates of nitrogen bases as lubricant dopes. 1

l The following examples set forth representative embodirnents of the process of preparingthiomolybdates use- 2,938,869 Patented May 331,

ful for the purposes of the present invention. In these examples, the percentages are by weight.

' EXAMPLE 1 There are successively prepared a normal solution of sodium thiomolybdate (one mol) in one liter of water and an aqueous four-normal solution of triethylamine hydrochloride (two mols) in one liter of water. One part by volume of the triethylamine hydrochloride solutionis poured in two parts by volume of the solution "of the thiomolybdate. There is thus obtained a precipitate of triethylamine thiomolybdatein theform of crystals of brick-red color.

. Analysis by calcination of the organic product leaves aresidue of MoO corresponding to 33.7% of the molybdate formed. The percentage of M00 calculate'd'from the formula[N(C H H MoS is 33.8% which is extremely close to that actually obtained. 1

EXAMPLE 2 v I I Heptylamine thiomolybdate is prepared in the form of brown-red crystals of double exchange between sodium thiomolybdate (1- mol) andlleptylamine hydrochloride (2 mols), after the manner described in Example 1. Analysis by calcination of the organic product leaves a residue of M00 corresponding to 31.5% of the thio molybdate formed. The percentage of M00 calculated from the formula (NH C H .H MoS is 31.7% which is extremely close to that actually obtained. I r

EXAMPLE 3 Methylpyridinium. thiomolybdate is prepared; in 1 the form of red crystals by precipitation from aisolution of sodium thiomolybdate (1 mol) with the theoreticalquantity (2 mols) of methylpyridiniurn sulfate, -after the man ner describedin Example 1. V Analysis by calcination of the organic product leaves a residue to M00 corresponding to,34.9% ofthethio molybdate formed. The percentage of M00; calculated from the formula (C H NhMoS is 35.0% which is'ex} tremely close to that actually'obtaine'd. I

EXAMPLE 4 Hexylpyridinium thiomolybdate is prepared in the form of red crystals by double exchange between hexylpyridin ium hydrobromide (2 mols) and sodium thiomolybdate (1 mol), after the manner described in Example 1.

Analysis by calcination of'the organieproduct leaves a residue of M00 corresponding to 28.3% of the thio; molybdate formed. The percentageof M00 calculated from the formula c,,H,,N ,M s, is[26.l%, which is very close to that actually obtained. I

' xA PLns DecyIene-LIO- dipyridiniuni thiomolybdate is was EXAMPLE 6 Hexyl-qu'inolinium thiomolybdate is obtained in the form of red crystals by double exchange between sodium molybdate (1 mol) and hexyl-quinolinium hydrobromide (2 mols), after the manner described in Example 1.

" Analysis by calcination of the organic product leaves a residue of M00, corresponding to 23.0% Of thgthiih molybdate formed. The percentage of M calculated from the formula (C H N) M0S iS is extremely close to that actually obtained.

7 EXAMPLE 7 By precipitation of an aqueous solution of sodium thiomolybdate (1 mol) with an aqueous solution of decylamine hydrochloride (2 mols), the decylamine thiomolybdateis obtained in the form of a very luminous orangecolored powder.

After calcination to a dull red heat, a residue of M00 remains which corresponds to 27.3% of the thiomolybdatefformed. The theoretical figure for such M00 residue, calculated from the formula (NHgCmHm) .HzMOS4 It will be understood that the invention covers application to thiomolybdates of other organic nitrogen bases than those mentioned, by way of example in the foregoing illustrative examples. Thus other operative thiomolybdates comprise:

' Coming now, more specifically, to the lubricants and lubricant-use aspects of the present invention:

The-thiomolybdates of organic bases ar 'e but little soluble in water and in alcohol, solutions. in the latter being of yellow orange color.

oils or in oils constituted by a mixture of esters of fatty acids and alcohols, or in a mixture obtained from trans-esterification of vegetable or animal oils with polyethylene glycol or polypropylene glycol or a higher alcohol, or in the synthetic products from the esterification of mono and polyalcohols with fatty acids'or from the esterification ofdiacids with monoalcohols. Particularly valuable are a solution of a nitrogenous thiomolybdate in a diol, glycol, polyalc'ohol or polyethyleneglycol. The lubricants thus obtained have the property of decomposing at temperature and pressures producedby friction.

Among others the following specific oils can be used as lubricantsaccording to the invention: castor oil, peanut oil, olive oil, ox-foot oil, fish oil, monooleates of polyethylene glycols, monoolcates of butylene glycols, monooleates of polypropylene glycols, monooleates of polytri methylene, glycols, palmitates of polypropylene glycols,

'dioleates' of: polyethylene glycols, butylene glycol, polypropylene glycols, polytrimethylene glycols; bishexyl sebacate, bishexyliadipate, bishexyl methyl adipate, bisheptyl sebacate, bisheptyl adipate, bisheptylmethyl adipatc, bisoctyl sebacate, bisoctyl adipate, bisoctyl methyl adipate, bisnonyl sebacate, bisnonyl adipate, bisnonyl On the other hand', the said thio'molybdates are soluble in vegetable or animal.

, are thus clear."

4 methyl adipate biSdecyI adipate, bisdecyl sebacate, bisdecyl methyl adipate, bisundecyl sebacate, bisundecyl adipate, bisundecyl methyl adipate, bisdodecyl sebacate, bisdodecyl adipate, bisdodecyl methyl adipate, decane diol, octane diol, hexane diol.

The solution of the organic thiomolybdates of the present invention in these oils can ,be established at various concentrations. As a rule, the higher the concentration of the organic thiomolybdates in the oils, the more intense is the lubricating power of the resultant product. On the other hand, experience has shown that very small concentrations of the order of 0.2%v bring about a notable increase in the lubricating power of the thus-established oil. In view of the high cost of the thiomolybdates, there is a limit, economically, to their concentration in the base oil, which limit is about 6% (on the basis of present economic conditions). According to the base 'oil employed and the lubricating performances which it is desired to achieve, it is presently preferred to incorporate into the oil a quantity of thiomolybdate of organic base representing about 0.2 to 6% by weight of such oil. Higher percentages may of course also be employed, if desired. I v The solutions thus prepared are stable in air, butpossess the property of decomposing at high temperature (above about f C.), depositing a brown-colored sulfur compound of molybdenum. This deposit fills the irregularities of the contact surfaces of the 'members being subjected to friction; it thus facilitates the sliding thereof, considerably reducing their coeflicient of friction and their wear. The numerous advantages which result from the utilization of these solutions in 'the field of lubrication Thus, for example, a 2% solution of the thiomolybdate of triethylamine in a polyethylene glycol of a molecular weight of 400 constitutes a lubricant of the first order. Testslcarriedout .on the Four-Ball Machineff described. by Boerlage in Engineering, July 14, 1933, page 46,-show that such lubricant makes it possible to attain directly pressures at kg. (26,000 kg./cm. taking into account the deformation of the diameter) without seizure of the machine, while the same polyethylene glycol used alone as lubricant without the addition of the thiomolybdate allows theattainment ofonly a pressureof' 110 kg. 1300 kg./'cm. with seizure occurring after 3.5 seconds. The principal results of these tests are tabulated in the following:

Tests on the Four-Ball Machine 7 A. POLYETHYLENEGLYCOL OF MOLECULAR WEIGHT g 400 (ALONE) V 1 Time Duration Co'eflioientol'Friction Load Applied Until of Selzinkg. Selzing lngin Beglnsin Seconds Before Maxl- After seconds seizing mum Selzing is Y 3' 0.08 l 0.35 0.06 g 6 4, 0.08 0.42 0.00

as as 0.00 0. 49 0.07

B. POLYETHYLENE GLYOOL OF MOLECULAR WEIGHT 400+2% 0F TRIETHYLAMINE THIOMOLYBDATE NOTE.T]1BS6 tests were carried out using new balls each time.

The difference in performance is even more distinct when the pressure is increased progressively'while lubricating continuously. The protective deposit formed by decomposition of the thiomolybdate under the influence of the temperature attained locally by the 'friction then becomes increasingly greater and makes it possible to obtain pressures on the Four-Ball Machine exceeding 300 kg. without seizure;

Following is another representative set of test results Tests on the Four-Ball Machine 0. soLurroN or 1% OCTYLAMINETHIOMOLYBDATE IN fQgLYETHYLENE GLYCOL or MOLECULAR WEIGHT Load applied (kg.) 260 290 300 310 Time Until Seizing Begins (Seconds). 60 60 0. 4 Coeflicient of Friction:

Before seizing 0. 11 0. 0.10 0. 10 Maximum 0. 0. 24 Aiter Seizlng 0. 06 0. 06 Diameter of Imprint (mm.) 0. 6 0. 6 1.0 1. 2

D. SOLUTION OF 1% DECYLAMINE THIOMOLYBDATE {obs POLYETHYLENE GLYCOL OF MOLECULAR WEIGHT E. SOLUTION OF 0.6% 0F METHYLPYRIDINIUM THIO- MOLYBDATE IN POLYETHYLENE GLYCOL OF MOLEC- ULAR WEIGHT 400 Load applied (kg.) 260 265 270 280 Time Until Seizing Begins (Seconds). 60 0. 2 0 0 Coeificient of Friction:

Before Selling..- 0. 10 0. 12 M m 0. 22 0. 26 0. 27 After seizingnu; 0. 06 0.06 0.07 Diameter of Imprint (mm) 0. 6 1. 1 1. 2 1. 2

F. SOLUTION OF 0.5% OF HEXYLPYRIDINIUM THIO- MOLYBDATE IN POLYETHYLENE GLYOOL OF MOLEC- ULAR WEIGHT 400 Load applied (kg) 260 280 290 295 300 Time Until Seizing Begins (Seconds).. 60 60 60 0 0 Coeflicient of Friction:

Before Seizing 0. l1 0. 11 0. 10 Maximum 0.29 0. 36 After S 0.06 0.08 Diameter of Imprint (mm.) 0. 7 0. 6 0. 7 1. 6 1. 6

G. BIS-RICINOLEATE OF POLYETHYLENE GLYCOL OF MOLECULAR WEIGHT 400 Load applied (Kg) 110 115 120 Time Until Selling Begins 60 60 Ooeflicient of Friction:

Before Seizing 0.08 0.10 0. Maximum 0. After Seizingl 0. Diameter of Imprint (mm.) 0. 4 0. 6 0

H. SOLUTION OF 1% OF OCTYLAMINE THIOMOLYBDATE IN BIS-RICINOLEATE OF POLYE'IHYLENE GLYCOL OF MOLECULAR WEIGHT 400 Load applied (Kg) 140 160 170 175 180 Time Until seizing Begins 60 60 60 0.6 0. 2 Coeflicient of Friction:

Before Seizing 0. 11 0.12 Maximum 0. 29 0. 27 After Seizin 0.07 0. 07 Diameter of Imprint (mm. 1. 2 1. 2

polyethylene glycol with a molecular weight of 400, to which was added sufiicient additive. to just saturate the solution. The resultsfollowz l. POLYETHYLFNE GLYCOL 400 .SATURATED WITH .THIOMOLYBD- A'IE OF TRIETHYLAMINE (2%) Tension applied,.volts Load, Couple 1 Wear: 0.06 mm.

2. POLYETHYLENE GLYOOL 400 SATURATED WITH HEXYLQUINOLINIUM THIOMOLYBDATE (0.25%)

Load,

1 Wear: 0.15 mm.

It will be evident from the foregoing that the invention is particularly applicable to the lubrication of metal parts of machines and the like.

Having thus disclosed the invention, What is claimed is:

1. A lubricant composition consisting essentially of from 94 to 99.8 parts by weight of a lubricant base selected from the group consisting of vegetable oil, animal oil, alkanediols having from 6 to 10 carbon atoms, fatty' acid esters wherein the fatty acid radical has from 6 to 18 carbon atoms and the alcohol part of the ester consists of from one to two radicals of an alcohol having from one to two hydroxyl groups and from 4 to 12 carbon atoms, and monobasic fatty acid alkanediol esters wherein the fatty acid radical has from 16 to 18 carbon atoms and wherein the alcohol part of the ester is a polyalkylene glycol radical wherein the alkylene group contains from 2 to 5 carbon atoms, and, dissolved therein, from 0.2 to 6 parts by weight of a thiomolybdate of an organic nitrogen base.

2. A lubricant composition consisting essentially of from 94 to 99.8 parts by weight of a vegetable oil and, dissolved therein, from 0.2 to 6 parts by weight of a thiomolybdate of an organic nitrogen base.

3. A lubricant composition consisting essentially of from 94 to 99.8 parts by weightv of an animal oil and, dissolved therein, from 0.2 to 6 parts by weight of a thiornolybdate of an organic nitrogen base;

4. A lubricant composition consisting essentially of from 94 to 99.8 parts by weight of a lubricant base consisting of an alkanediol having from 6 to 10 carbon atoms, and, dissolved therein, from 0.2 to 6 parts by weight of a thiomolybdate of an organic nitrogen base.

5. A lubricant composition consisting essentially of from 94 to 9918 parts by weight of a lubricant base consisting of a fatty acid ester wherein the fatty acid radical has from 6 to 18 carbon atoms and the alcohol part of the ester consists of from one to two radicals of an alcohol having from one to two hydroxyl groups and from 4 to 12 carbon atoms, and, dissolved therein, from 0.2

to 6 parts by weight of a thiomolybdate of an organic t a 6 o 18c honsai msans ha a ohol' part qtthe ester is a p p py l'ml; radical; and; issolved therein, from 0.2 to 6 parts by weight of a thiomolybdate of an organic nitrogenbase. v ;c I

8. A lubricant composition consisting essentially of from 94 to 99.8 parts by weightof. a dibasic fatty acid alkyl ester wherein the fatty acid radicalhas from 6 to 10 carbon atoms and the-alkyl-parflof the ester has from 6 to 12 carbon atoms, and, dissolved. therein, from 0.2 to 6 parts by weight of a thiomolybdate of an organic nitrogen base.

9. A lubricants composition. consisting essentially of from 94 to 99.8 parts by weight of a monooleate of a a a a l a p lyethy eaa. glycal, nd- S9lY 1.1hEii a, fQm; 0,2. to 6 parts, by wei ht of, afi hiamalybda e of aa v ganiqnitrogen'base. V

I References iCitedimthe iile- (11mm; :pateiit- UNITED- STATES PATENTS: 2,421,543

Debucquet et al Bulletin de la Ste Chemique de France, 1932, 51', 1571. 1 

1. A LUBRICANT COMPOSITION CONSISTING ESSENTIALLY OF FROM 94 TO 99.8 PARTS BY WEIGHT OF A LUBRICANT BASE SELECTED FROM THE GROUP CONSISTING OF VEGETABLE OIL, ANIMAL OIL, ALKANEDIOLS HAVING FROM 6 TO 10 CARBON ATOMS, FATTY ACID ESTERS WHEREIN THE FATTY ACID RADICAL HAS FROM 6 TO 18 CARBOM ATOMS AND THE ALCOHOL PART OF THE ESTER CONSISTS OF FROM ONE TO TWO RADICAL OF AN ALCOHOL HAVING FROM HAVING FROM ONE TO RWO HYDROXYL GROUPS AND FROM 4 TO 12 CARBON ATOMS, AND MONOBASIC FATTY ACID AKLANEDIOL ESTERS WHEREIN THE FATTY ACID RADICAL HAS FROM 16 TO 18 CARBON ATOMS AND WHEREIN THE ALCOHOL PART OF THE ESTER IS A POLYTAINS FROM 2 TO 5 CARBON ATOMS, AND, DISSOLVED THEREIN, FROM 0.2 TO 6 PARTS BY WEIGHT OF A THIOMOLYBDATE OF AN ORGANIC NITROGEN BASE. 